Humboldt County, CA

ZIP 95540

In ZIP 95540, 6 of the 12 things we check have at least one part graded D or F.

• Drinking water: Riverbend Mobile Home Park meets every EPA legal limit; 1 contaminant is above health goals, led by lead at 31× California’s Public Health Goal.
• Closer to Superfund sites than 0% of U.S. neighborhoods, with no listed site within 10 miles of its center.
• Largest share of modeled toxic air from industry: Pg&E Humboldt Bay Power Plant (100%), mostly acetaldehyde.
• Fine particles (PM2.5) average 9.5 µg/m³; the WHO guideline is 5 and the EPA annual standard is 9.
• About 15,274 kg of agricultural pesticides are applied in the county each year.

Grades for ZIP 95540

• Superfund sites nearbyA
• Factories and industrial sitesB to C
• Oil and gas wellsA to D
• Parks and nature nearbyB to D
• Air qualityC to F
• Drinking water qualityA to F
• Pesticide useC to D
• Neighborhood health statusD
• Past wildfire impactsA
• Past flood impactsA
• Noise levelsA
• Radiation signalsB to C

Based on 5 census tracts · compiled September 10, 2026 · how each grade works and its sources

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